Treatment of hydrocarbon oils



l atent raaar'r'os r: Wayne L. Benedict and Jacob Elston z,

Chicago, m,

aooson oiLs ore to Universal'Oii Products Company, Chicao, BL, a corporation of Delawere No Brawing. Application March 22, 1939, Serial No. 263,416

6 Claims.

The invention particularly relates to the treatment of hydrocarbon distillates produced by straight-run distillation or cracking of heavy petroleum oils, or hydrocarbon oils of a similar nature from other sources, such as shale oils, coal tar distillates, etc. More specifically, it is directed toward improvements in methods of sweetening petroleum distillates of gasoline boiling range, although oils of the naphtha, kerosene and gas 011 range may also be treated.

Practically all gasoline requires some form of refining before it is marketable. In general, these refining methods are directed toward preventing the formation of gum and color, and loss of antiknock during periods of storage, as well as to improve the odor.

A sweetening treatment is required in most cases regardless of the other refining method used. Methods which have been used for the sweetening of gasolines include the sodium plumbite or doctor method, and hypochlorite sweetening, a method which has found application primarily with straight-run and natural gasolines. Another process which has gained in commercial importance in the last several years makes use of copper-containing reagents. It is with this type of process that the present invention is concerned.

In one specific embodiment the invention comprises sweetening hydrocarbon distillates with a copper-containing reagent, then treating in the presence of a solid contact reagent comprising a major portion of a precipitated silica mass and a minor portion 'of a sulfide of a heavy metal above hydrogen in the electro-chemical series.

The copper sweetening methods which have been found useful and which are included in the scope of the present invention within the meaning of the term copper sweetening include the use of solutions of copper salts, such as cupric chloride or mixtures of copper salts with sodium and ammonium chloride, for example, solutions of sodium chloride or ammonium chloride with copper sulfate; mechanical mixtures of copper sulfate and the chlorides of alkalinous materials mixed with spacing agents such as fuller's earth, pumice, and the like; and carriers of the nature of fullers earth, pumice, etc. which have been impregnated with copper salts. The minute quantitles of impurities involved in copper sweetening make the investigation of the exact course of the reactions difilicult to follow. However, they apparently involve the oxidation of mercaptans to' disulfides through the intermediate step of copper mercaptide formation accompanied by the reduction of the cupric copper to the cuprous form. In most of the copper sweetening processes the cuprous copper is regenerated. to the cupric form by the continuous addition of oxygen or air or other oxygen-containing gas. This may be done either simultaneously with the sweetening reaction or as a separate regeneration step. In most cases the regeneration occurs at room temperature.

During the time that the gasoline is in contact with the copper sweetening reagent, certain sec-- ondary reactions occur which are of an unknown nature, but which result in the introduction in the sweetened gasoline of small amounts of cop per. The exact form in which this copper is present is not known. If left in the gasoline the copper brings about the formation of color and reduces the susceptibility of the gasoline to inhibitors, as well as markedly reducing its storage stability. Apparently the copper compound acts as an oxidation catalyst if present in more than the barest traces. It is with the, removal of copper from the sweetened gasoline that the present invention is specifically concerned.

Among the methods which have been suggested for eliminating the copper compounds is the contacting of said gasolines with heavy metal sulfides above hydrogen in the clectro-chemical series, such as have been described in U. 8. Patent No. 2,102,878. In general, the sulfides as described in this patent aresultable for restoring the properties of copper sweetened gasolines to their original quality. The sulfides which have been found especially useful in this process include those of zinc, iron, chromium, manganese, cadmium, cobalt, nickel, tin, lead, etc. It has been our experience, however, that certain gasolines after copper sweetening are not completely restored to their original properties by means of these reagents, although substantial improvement is obtained in all known cases.

. The present invention consists in an improvement in the use of metal sulfides after copper sweetening wherein the sweetened gasoline is contacted with a sulfosilicate of a heavy metal,

particularly of zinc. Compounds of iron, cadmium, cobalt, nickel, tin, antimony, and lead are also useful. It should be understood that whileall of these compounds have a beneficial effect and may be used alternatively, they are.

may be compressed by the addition of a salt of the heavy metal to be used, plus sufiicient acid such as hydrochloric acid to complete the precipitation, followed by filtration of the mixture. The amount of metal salt used is normally less than a mol equivalent of the silicate present. The mixture is again suspended in water and an alkali added, preferably ammonium hydroxide, until the mixture is slightly alkaline. Hydrogen sulfide is then passed through the wet mixture until sulfide formation is complete and'the mixed suspended material filtered and dried, preferably in the absenceof air. Another method of preparation is to precipitate a gel from sodium silicate solution by means of an acid, wash the resultant gel until it is substantially free of alkali metal compounds, add the salt of the desired metal to a suspension of said gel, precipitate with ammonium hydroxide and finally treat with hydrogen sulfide as before. Still another method consists in precipitation of the gel as described above and formation of the sulfosilicate by use of barium or calcium sulfide as precipitants instead of hydrogen sulfide, followed by filtration, drying and calcining. There are other methods obvious to chemists for preparing the sulfo-silicates and these are considered to be within the scope of the present invention. A method of preparing zinc sulfo-silicates in addition to those mentioned involves the use of zinc silicate ores, such as zincite. The reagent is prepared by grinding the mineral zincite to a powder and treating it with hydrochloric acid to form a gel, followed by the steps described above for forming the sulfosilicate.

zinc and it is sometimes desirable to mix the gel with a sodium silicate solution to decrease the ratio of zinc to silica in the mixture, and then converting to the sulfosilicate by adding hydrogen sulfide, etc.

It has been found that sulfosilicate reagents prepared in this way are more reactive than the sulfide reagents of the above mentioned patent. The sulfosilicates may be used in the form of powders for contacting with the gasoline, or they into granules or pellets. Each of these methods has advantages and all have been used in applying the process.

The term sulfosilicate is understood to cover 7 compounds prepared according to the general method above described. The term is not intended to indicate in any way the chemical relationship between the silica component and the metal sulfide component of the reagent. Such relationship is not known or clearly understood and may comprise an intimate mechanical mixture or an actual chemical combination.

The following example is given by way of iilustrating the usefulness of the process and its advantage over the existing methods, but should not be construed as limiting the process to the exact conditions given herein. H

The metal sulfosilicate used in the present example was made by precipitation or a solution' of water glass with a zinc chloride solution to which a small amount of hydrochloric acid had been added until the mixture was faintly acid, and the addition of ammonium hydroxide solution until the mixture was alkaline to litmus. A

small amount of ammonium sulfide solution was The amount of silica available in the zincite is somewhat low compared to the then added and hydrogen sulfide was bubbled through for '2 hours, the mixture beingwarmed to F. during this time. The resulting mixture was filtered and washed with water. The reagent was'then dried at 220 F. in the absence of anysubstantial amounts of air. It was compressed and broken into granules of 10-60 mesh and used as a packing material in the secondary treating tower of a copper sweetening plant.

West Texas cracked gasoline was sweetened by passage together with air through a mixture of copper sulfate, ammonium chloride and pumice, the residual air was separated. and the gasoline stream divided into two portions: One was passed through a secondary reagent consisting of zinc sulfide mechanically dispersed on pumice, and the other stream passed through the secondary reagent described above. The results of these tests are shown in the following table.

, These results as indicated by the" color and induction periods show that the zinc sulfide reagent did not remove all of the undesirable compounds but that this was accomplished by th zinc sulfosilicate secondary reagent.

We claim as our invention:

1. A process for refining hydrocarbon distillate which comprises sweetening said distillate with a copper-containing reagent, separating the distillate, treating said distillate in the presence of a heavy metal sulfosilicate to remove copper therefrom, and recovering the sweet gasoline.

2. A process for refining hydrocarbon distillate which comprises sweetening said distillate with a copper-containing reagent, separating the distillate, treating same in the presence of a sulfosilicate of a heavy metal selected from the group consisting of zinc, iron, cadmium, cobalt, nickel, tin, antimony, and lead, to remove copper therefrom, and recovering the sweet gasoline.

3. The process of claim 2 wherein the sulfosilicate comprises essentially zinc.

4. In the copper sweetening of hydrocarbon oils, the method of removing copper from the oil which comprises treating the copper sweetened oil with a sulfosilicate of a heavy metal.

5. In the copper sweetening of hydrocarbon oils, the method of removing copper from the oil which comprises treating the copper sweetened oil with a sulfosilicate of a heavy metal above hydrogen in the electro-chemical series.

6. In the copper sweetening of hydrocarbon oils, the method of removing copper from the oil which comprises treating the copper sweetened oil with zinc sulfosilicate.

WAYNE L. BENEDICT. JACOB ELSTON AHLBERG. 

